1/* $OpenBSD: imsg.c,v 1.16 2017/12/14 09:27:44 kettenis Exp $ */
2
3/*
4 * Copyright (c) 2003, 2004 Henning Brauer <[email protected]>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19#include <sys/types.h>
20#include <sys/socket.h>
21#include <sys/uio.h>
22
23#include <errno.h>
24#include <stdlib.h>
25#include <string.h>
26#include <unistd.h>
27
28#include "compat.h"
29#include "imsg.h"
30
31int imsg_fd_overhead = 0;
32
33static int imsg_get_fd(struct imsgbuf *);
34
35void
36imsg_init(struct imsgbuf *ibuf, int fd)
37{
38 msgbuf_init(&ibuf->w);
39 memset(&ibuf->r, 0, sizeof(ibuf->r));
40 ibuf->fd = fd;
41 ibuf->w.fd = fd;
42 ibuf->pid = getpid();
43 TAILQ_INIT(&ibuf->fds);
44}
45
46ssize_t
47imsg_read(struct imsgbuf *ibuf)
48{
49 struct msghdr msg;
50 struct cmsghdr *cmsg;
51 union {
52 struct cmsghdr hdr;
53 char buf[CMSG_SPACE(sizeof(int) * 1)];
54 } cmsgbuf;
55 struct iovec iov;
56 ssize_t n = -1;
57 int fd;
58 struct imsg_fd *ifd;
59
60 memset(&msg, 0, sizeof(msg));
61 memset(&cmsgbuf, 0, sizeof(cmsgbuf));
62
63 iov.iov_base = ibuf->r.buf + ibuf->r.wpos;
64 iov.iov_len = sizeof(ibuf->r.buf) - ibuf->r.wpos;
65 msg.msg_iov = &iov;
66 msg.msg_iovlen = 1;
67 msg.msg_control = &cmsgbuf.buf;
68 msg.msg_controllen = sizeof(cmsgbuf.buf);
69
70 if ((ifd = calloc(1, sizeof(struct imsg_fd))) == NULL)
71 return (-1);
72
73again:
74 if (getdtablecount() + imsg_fd_overhead +
75 (int)((CMSG_SPACE(sizeof(int))-CMSG_SPACE(0))/sizeof(int))
76 >= getdtablesize()) {
77 errno = EAGAIN;
78 free(ifd);
79 return (-1);
80 }
81
82 if ((n = recvmsg(ibuf->fd, &msg, 0)) == -1) {
83 if (errno == EINTR)
84 goto again;
85 goto fail;
86 }
87
88 ibuf->r.wpos += n;
89
90 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
91 cmsg = CMSG_NXTHDR(&msg, cmsg)) {
92 if (cmsg->cmsg_level == SOL_SOCKET &&
93 cmsg->cmsg_type == SCM_RIGHTS) {
94 int i;
95 int j;
96
97 /*
98 * We only accept one file descriptor. Due to C
99 * padding rules, our control buffer might contain
100 * more than one fd, and we must close them.
101 */
102 j = ((char *)cmsg + cmsg->cmsg_len -
103 (char *)CMSG_DATA(cmsg)) / sizeof(int);
104 for (i = 0; i < j; i++) {
105 fd = ((int *)CMSG_DATA(cmsg))[i];
106 if (ifd != NULL) {
107 ifd->fd = fd;
108 TAILQ_INSERT_TAIL(&ibuf->fds, ifd,
109 entry);
110 ifd = NULL;
111 } else
112 close(fd);
113 }
114 }
115 /* we do not handle other ctl data level */
116 }
117
118fail:
119 free(ifd);
120 return (n);
121}
122
123ssize_t
124imsg_get(struct imsgbuf *ibuf, struct imsg *imsg)
125{
126 size_t av, left, datalen;
127
128 av = ibuf->r.wpos;
129
130 if (IMSG_HEADER_SIZE > av)
131 return (0);
132
133 memcpy(&imsg->hdr, ibuf->r.buf, sizeof(imsg->hdr));
134 if (imsg->hdr.len < IMSG_HEADER_SIZE ||
135 imsg->hdr.len > MAX_IMSGSIZE) {
136 errno = ERANGE;
137 return (-1);
138 }
139 if (imsg->hdr.len > av)
140 return (0);
141 datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
142 ibuf->r.rptr = ibuf->r.buf + IMSG_HEADER_SIZE;
143 if (datalen == 0)
144 imsg->data = NULL;
145 else if ((imsg->data = malloc(datalen)) == NULL)
146 return (-1);
147
148 if (imsg->hdr.flags & IMSGF_HASFD)
149 imsg->fd = imsg_get_fd(ibuf);
150 else
151 imsg->fd = -1;
152
153 memcpy(imsg->data, ibuf->r.rptr, datalen);
154
155 if (imsg->hdr.len < av) {
156 left = av - imsg->hdr.len;
157 memmove(&ibuf->r.buf, ibuf->r.buf + imsg->hdr.len, left);
158 ibuf->r.wpos = left;
159 } else
160 ibuf->r.wpos = 0;
161
162 return (datalen + IMSG_HEADER_SIZE);
163}
164
165int
166imsg_compose(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid, pid_t pid,
167 int fd, const void *data, uint16_t datalen)
168{
169 struct ibuf *wbuf;
170
171 if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
172 return (-1);
173
174 if (imsg_add(wbuf, data, datalen) == -1)
175 return (-1);
176
177 wbuf->fd = fd;
178
179 imsg_close(ibuf, wbuf);
180
181 return (1);
182}
183
184int
185imsg_composev(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid, pid_t pid,
186 int fd, const struct iovec *iov, int iovcnt)
187{
188 struct ibuf *wbuf;
189 int i, datalen = 0;
190
191 for (i = 0; i < iovcnt; i++)
192 datalen += iov[i].iov_len;
193
194 if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
195 return (-1);
196
197 for (i = 0; i < iovcnt; i++)
198 if (imsg_add(wbuf, iov[i].iov_base, iov[i].iov_len) == -1)
199 return (-1);
200
201 wbuf->fd = fd;
202
203 imsg_close(ibuf, wbuf);
204
205 return (1);
206}
207
208/* ARGSUSED */
209struct ibuf *
210imsg_create(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid, pid_t pid,
211 uint16_t datalen)
212{
213 struct ibuf *wbuf;
214 struct imsg_hdr hdr;
215
216 datalen += IMSG_HEADER_SIZE;
217 if (datalen > MAX_IMSGSIZE) {
218 errno = ERANGE;
219 return (NULL);
220 }
221
222 hdr.type = type;
223 hdr.flags = 0;
224 hdr.peerid = peerid;
225 if ((hdr.pid = pid) == 0)
226 hdr.pid = ibuf->pid;
227 if ((wbuf = ibuf_dynamic(datalen, MAX_IMSGSIZE)) == NULL) {
228 return (NULL);
229 }
230 if (imsg_add(wbuf, &hdr, sizeof(hdr)) == -1)
231 return (NULL);
232
233 return (wbuf);
234}
235
236int
237imsg_add(struct ibuf *msg, const void *data, uint16_t datalen)
238{
239 if (datalen)
240 if (ibuf_add(msg, data, datalen) == -1) {
241 ibuf_free(msg);
242 return (-1);
243 }
244 return (datalen);
245}
246
247void
248imsg_close(struct imsgbuf *ibuf, struct ibuf *msg)
249{
250 struct imsg_hdr *hdr;
251
252 hdr = (struct imsg_hdr *)msg->buf;
253
254 hdr->flags &= ~IMSGF_HASFD;
255 if (msg->fd != -1)
256 hdr->flags |= IMSGF_HASFD;
257
258 hdr->len = (uint16_t)msg->wpos;
259
260 ibuf_close(&ibuf->w, msg);
261}
262
263void
264imsg_free(struct imsg *imsg)
265{
266 freezero(imsg->data, imsg->hdr.len - IMSG_HEADER_SIZE);
267}
268
269static int
270imsg_get_fd(struct imsgbuf *ibuf)
271{
272 int fd;
273 struct imsg_fd *ifd;
274
275 if ((ifd = TAILQ_FIRST(&ibuf->fds)) == NULL)
276 return (-1);
277
278 fd = ifd->fd;
279 TAILQ_REMOVE(&ibuf->fds, ifd, entry);
280 free(ifd);
281
282 return (fd);
283}
284
285int
286imsg_flush(struct imsgbuf *ibuf)
287{
288 while (ibuf->w.queued)
289 if (msgbuf_write(&ibuf->w) <= 0)
290 return (-1);
291 return (0);
292}
293
294void
295imsg_clear(struct imsgbuf *ibuf)
296{
297 int fd;
298
299 msgbuf_clear(&ibuf->w);
300 while ((fd = imsg_get_fd(ibuf)) != -1)
301 close(fd);
302}
303